#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include "syscall.h"

int ttyname_r(int fd, char *name, size_t size)
{
    struct stat st1, st2;
    char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
    ssize_t l;

    if (!isatty(fd)) return errno;

    __procfdname(procname, fd);
    l = readlink(procname, name, size);

    if (l < 0) return errno;
    else if (l == size) return ERANGE;

    name[l] = 0;

    if (stat(name, &st1) || fstat(fd, &st2))
        return errno;
    if (st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino)
        return ENODEV;

    return 0;
}
